Water-soluble, predominantly oil-free alkyd resins

摘要

The invention relates to predominantly oil-free polyester resins which can be used in binders for water-borne paints. The long-chain modifiers in the resins are not fatty acids, but instead epoxyalkanes having 8-20 carbon atoms and containing a terminal or internal epoxide group. Further characteristic features are an acid number of between 5 and 35 and a hydroxyl number of greater than 200, due in part to terminal 2,3-dihydroxypropyl groups. The resins are prepared by a process in which a condensation product having an acid number of between 40 and 120 is adjusted to the desired acid number in the final step by the addition reaction of glycide with the acid groups.